Antigenic variation in influenza virus.
نویسندگان
چکیده
/3-c-p region with a cross-over bust be that of phydroxybenzoate hydroxylase. The only conventional nucleotide-binding site is occupied by FAD, and NADP+ binds to the enzyme together with FAD for turnover. It may be significant that for the two observed variant coenzyme sites, those of hexokinase and 6-phosphogluconate dehydrogenase, the details of coenzyme binding are said to be ‘different’ (Steitz et al., 1981, Abdallah et al., 1979). It will be of interest to see whether the binding of NADP appears to be ‘different’ in p-hydroxybenzoate hydroxylase. In conclusion, the minimum requirement for the most frequently observed mode of coenzyme binding is a sheet with a twist and a helix on either side of it. The adenine portion alone requires only a sheet which twists and a single helix, but one which comes from a Fa-! unit of the second half of the binding site. The use of two secondary structural units with a given relationship to each other provides a stable site but one which may be modified. Since specificity of binding is required as well as stability for enzyme function (6-phosphogluconate dehydrogenase will not bind NAD+), an analysis of the differences between the various nucleotide-binding sites and the conformations of the bound nucleotides should contribute as much as the observation of similarities to an understanding of enzyme activity. Since this paper was originally presented, an electron-density map, modified by the procedure of Bhat 8z Blow (1982) has now been interpreted (Adams et al., 1983). This has resolved the ambiguity shown in Fig. 2, indicating that the preferred topology (Fig. 2a) is the correct one.
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عنوان ژورنال:
- Biochemical Society transactions
دوره 11 4 شماره
صفحات -
تاریخ انتشار 1983